Silicon wafers for producing oxide layers of high breakdown strength and process for the production thereof

Abstract

Silicon wafers and a process for the production thereof which produces was having intrinsic gettering action and on which thin oxide layers with high breakdown strength can be produced. During the production, the wafers are subjected to a treatment which smooths the wafer surface, for example, by repolishing, after the intrinsic getters have been produced in the interior of the wafer. Oxide layers subsequently deposited are outstanding for an increased breakdown strength compared with untreated wafers.

What is claimed is: 
     
       1. A process for producing an oxide layer of high breakdown strength on a semiconductor wafer having an interior thereof exhibiting regions of gettering action, which has been produced by a heat treatment, comprising the steps of: heating the semiconductor wafer to produce oxygen precipitations exhibiting an intrinsic gettering action in the interior of the semiconductor wafer;   smoothing at least one surface of the semiconductor wafer to reduce surface irregularities; and   heating the semiconductor wafer in an oxygen-container atmosphere for a predetermined time to form the oxide layer on said at least one surface after smoothing thereof.   
     
     
       2. The process as set forth in claim 1, wherein compounds formed on the at least one surface of the wafer are removed by etching prior to the smoothing treatment. 
     
     
       3. The process as claimed in claim 1, wherein the smoothing treatment is a polishing step. 
     
     
       4. The process as claimed in claim 3, wherein a surface layer up to 10 μm thick is removed by the polishing step. 
     
     
       5. The process as claimed in claim 1, wherein the smoothing treatment is a polishing step effecting the production of a haze-free wafer surface. 
     
     
       6. The process as claimed in claim 5, wherein a surface layer up to 10 μm thick is removed by the polishing step. 
     
     
       7. The process as claimed in claim 1, wherein the smoothing treatment is carried out by irradiating the surface with electromagnetic radiation. 
     
     
       8. The process as claimed in claim 7, wherein the electromagnetic radiation is light radiation. 
     
     
       9. The process as claimed in claim 1, wherein the smoothing treatment is carried out by exposure to etching solutions. 
     
     
       10. A process for producing oxide layers of high breakdown strength on the surface of semiconductor wafers comprising: heating the semiconductor wafers in an oxygen-free atmosphere at a temperature in the range of 1,100°-1,200° C. for a first predetermined time;   cooling the semiconductor wafers to a temperature in the range of 700°-800° C. and introducing an oxygen-containing atmosphere after said heating in an oxygen-free atmosphere and subsequently re-heating the semiconductor wafers for a second predetermined time at a temperature in the range of 1,000°-1,200° C.;   etching-off an oxide layer formed by heating the semiconductor in the oxygen-containing atmosphere;   smoothing at least one surface of the semiconductor to reduce surface irregularities; and   heating the semiconductor wafer in an oxygen-containing atmosphere for a third predetermined time to form the oxide layer on said at least one surface after said smoothing thereof.   
     
     
       11. The process as claimed in claim 10, wherein said first predetermined time is approximately 4-8 hours. 
     
     
       12. The process as claimed in claim 10, wherein said second predetermined time is approximately 1-10 hours. 
     
     
       13. A process for producing oxide layers of high breakdown strength on the surface of semiconductor wafers comprising: heating the semiconductor wafers in a oxygen-free atmosphere at a first predetermined temperature for approximately 4-8 hours;   cooling the semiconductor wafers to a temperature in the range of 700°-800° C. and introducing an oxygen-containing atmosphere after said heating in an oxygen-free atmosphere and subsequently re-heating the semiconductor wafers for approximately 1-10 hours to a second predetermined temperature;   etching-off an oxide layer formed by heating the semiconductor in the oxygen-containing atmosphere;   smoothing at least one surface of the semiconductor to reduce surface irregularities; and   heating the semiconductor wafer in an oxygen-containing atmosphere for a predetermined time to form the oxide layer on said at least one surface after said smoothing thereof.   
     
     
       14. The process as claimed in claim 13, wherein said first predetermined temperature is a temperature in the range of 1,100°-1,200° C. 
     
     
       15. The process as claimed in claim 13, wherein said second predetermined temperature is a temperature in the range of 1,000°-1,200° C. 
     
     
       16. A silicon wafer comprising: an interior containing oxygen precipitations exhibiting an intrinsic gettering action; and,   a front side and a rear side, at least one of said front side or said rear side having been given a polishing treatment before the formation of said interior and a smoothing treatment after the formation of said interior.   
     
     
       17. The silicon wafer as claimed in claim 16, having a wafer surface with gettering action situated opposite a wafer surface given a smoothing treatment. 
     
     
       18. The silicon wafer as claimed in claim 16, having surfaces situated opposite each other which have been give a smoothing treatment.